Effect of glucose on Listeria monocytogenes biofilm formation, and assessment of the biofilm's sanitation tolerance.

Listeria monocytogenes is an important cause of human foodborne infections and its ability to form biofilms is a serious concern to the food industry. To reveal the effect of glucose conditions on biofilm formation of L. monocytogenes, 20 strains were investigated under three glucose conditions (0.1, 1.0, and 2.0% w v(-1)) by quantifying the number of cells in the biofilm and observing the biofilm structure after incubation for 24, 72, and 168 h. In addition, the biofilms were examined for their sensitivity to sodium hypochlorite. It was found that high concentrations of glucose reduced the number of viable cells in the biofilms and increased extracellular polymeric substance production. Moreover, biofilms formed at a glucose concentration of 1.0 or 2.0% were more resistant to sodium hypochlorite than those formed at a glucose concentration of 0.1%. This knowledge can be used to help design the most appropriate sanitation strategy.

Effects of music listening and relaxation instructions on arousal changes and the working memory task in older adults.

The purpose of this study was to examine the effects of subject-preferred music and relaxation instructions on older adults' arousal and working memory. Fifteen female older adults participated in 10 minutes of all 3 experimental conditions: (a) subject-preferred music, (b) relaxation instructions, and (c) silence control. Four subcategories of arousal level, energy, tiredness, tension, and calmness, were measured before and after experimental treatment using the Activation-Deactivation Adjective Check List by Thayer (1978). After each experimental condition, subjects had a working memory test by Daneman and Carpenter (1980). Results of the 2 x 3 repeated measures analysis of variances indicated that music increased subjects' energy levels, but relaxation and silence significantly decreased energy levels. Relaxation and silence increased their tiredness and calmness levels. All experimental conditions decreased subjects' tension levels. The scores in the working memory test were not significantly different among experimental conditions. Results did not indicate clear relationships between four subcategories of arousal levels and working memory scores. Results indicated that subject-preferred music has potentials to increase older adults' energetic arousal and reduce tension.

The effects of music listening after a stressful task on immune functions, neuroendocrine responses, and emotional states in college students.

The purpose of this study was to examine the effects of listening to high-uplifting or low-uplifting music after a stressful task on (a) immune functions, (b) neuroendocrine responses, and (c) emotional states in college students. Musical selections that were evaluated as high-uplifting or low-uplifting by Japanese college students were used as musical stimuli. Eighteen Japanese subjects performed stressful tasks before they experienced each of these experimental conditions: (a) high-uplifting music, (b) low-uplifting music, and (c) silence. Subjects' emotional states, the Secretory IgA (S-IgA) level, active natural killer (NK) cell level, the numbers of T lymphocyte CD4+, CD8+, CD16+, dopamine, norepinephrine, and epinephrine levels were measured before and after each experimental condition. Results indicated low-uplifting music had a trend of increasing a sense of well-being. High-uplifting music showed trends of increasing the norepinephrine level, liveliness, and decreasing depression. Active NK cells were decreased after 20 min of silence. Results of the study were inconclusive, but high-uplifting and low-uplifting music had different effects on immune, neuroendocrine, and psychological responses. Classification of music is important to research that examines the effects of music on these responses. Recommendations for future research are discussed.